Production of color masking images using p-phenylenediamine mask-forming compounds



United States Patent Orifice 3,535,113 Patented Oct. 20, 1970 3,535,113 PRODUCTION OF COLOR MASKING IMAGES USlNG p-PHENYLENEDIAMHNE MASK-FORM- ING COMPOUNDS Jan .laeken, Hove, and Wilhelmus .lanssens, Aarscllot,

Belgium, assignors to Gevaert-Agfa N.V., Mortsei, Belgium, a Belgian company No Drawing. Filed Jan. 18, 1967, Ser. No. 610,023 Claims priority, application Great Britain, Jan. 18, 1966, 2,241/66 Int. Cl. G03c 7/18 US. Cl. 96-9 Claims ABSTRACT OF THE DISCLOSURE Forming a red light-absorptive dyestuir by oxidative coupling of a pyrazolone color coupler with an N,N- dialkyl-p-phenylenediamine derivative, the phenylene nucleus at positions adjacent the non-tertiary amino group being substituted with a substituent sterically hindering the amino group. Where the amino group is secondary the substituent thereon is adapted to split off during the oxidating coupling reaction. The dyestulf can be used to form a mask image for correcting the color in a color photographic element. Color photographic elements incorporating such compounds are also disclosed.

The present invention relates to the production of photographic colour images, more particularly to a process of colour correction utilizing an integral masking procedure.

It is known that dyes formed by colour development in the subtractive multicolour process do not transmit all of the light which they for practical demands have to transmit for a true colour reproduction.

The cyan dye, which should absorb red light and transmit green and blue light, usually absorbs to a minor degree green and blue light together with a major amount of red light. The magenta dye, which should absorb green light and transmit blue and red light, usually absorbs to a minor degree red and blue light together with a major amount of green light. The yellow dye, which should absorb blue light and transmit green and red light, is usually satisfactory.

Due to the not completely correct light absorption by the dyes formed on colour development at the exposed areas of the silver halide emulsion, it is impossible to obtain a print containing a true reproduction of the colours of the original. Correction for the unwanted side-absorptions in the printing process is therefore desirable. This is usually done by masking the side-absorptions of the dye image by the formation of a mask image absorbing light in the range of the said side-absorptions to practically the same extent as said side-absorptions and having a gradation opposite to that of the primary dye image.

Since separate masks are difficult to register with the colour transparency, it is desirable that the mask be integral with the coloured images.

According to one technique e.g. described in the US. patent specification 2,860,974 coloured mask images are automatically formed in photographic colour materials by the use of a coloured colour coupler absorbing light in the region of side-absorption of the dye formed with said colour coupler on colur development. Thus, according to that technique the mask image is formed by the coloured colour coupler itself, which is left on the nonexposed areas after colour development.

According to another technique wherein use is made of common colourless colour couplers, the colour coupler which is left, in the non-exposed areas after image-wise exposure and primary colour development of the silver halide emulsion layer, is treated oxidatively in the presence of a so-called masking compound for coupling therewith so as to form a masking dyestuff. The oxidative treatment usually is carried out in a photographic bleaching bath, e.g. a potassium hexacyanoferrateflll) containing alkaline aqueous solution used for removing the silver metal formed by development. Such a technique is described e.g. in our UK. patent specifications 880,862, 975,930, 975,932, 975,939 and 975,940.

According to an embodiment described in the UK. patent specification 975,932 a colour corrected image is formed in a photographic element comprising a silver halide emulsion layer and a colour coupler, e.g. a colour coupler for magenta of the pyrazolone type, which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a primary dye image, more particularly a magenta dye image which absorbs a major proportion of light in the green region of the visible spectrum, and undesirably absorbs a minor proportion of light in the blue region of the visible spectrum, by treating the exposed and colour-developed photographic element with an oxidizing solution, such as a photographic bleaching bath, in the presence of a compound which oxidatively couples with the residual colour coupler, whereby a secondary dye image is formed more particularly a yellow dye image, having a gradation opposite to that of said primary dye image, and absorbin glue light but transmitting substantially all the light in the green region of the visible spectrum.

It is an object of the present invention to provide a method of forming a colour-corrected image in a photographic element having at least one silver halide emulsion layer containing a colourless colour coupler of the pyrazolone type which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a primary dye image, more particularly a magenta dye image, which absorbs a major proportion of light in the green region of the visible spectrum, and undesirably absorbs a minor proportion of light in the red region of the visible spectrum.

That object has been accomplished by forming a dye stuff substantially absorbing in the red region of the visible spectrum by the oxidative copulation of the colourless magenta-forming colour coupler of the pyrazolone type, which is left after the colour development with a compound corresponding to the following general formula:

R represents a hydrogen atom, or a monovalent organic group such as an alkyl group, an aralkyl group or an aryl group, or a bivalent organic group linked to an ortho-atom of the aromatic group represented by A including these groups in substituted form:

R represents a monovalent organic radical such as an alkyl group, an aralkyl group or an aryl group, or a bivalent organic group linked to an ortho-atom of the aromatic group represented by A, including these groups in substituted form,

R repreesnts a.hydrogen atom, or a substituent which splits 01f by said oxidative copulation, and

A represents an aromatic group, which in p-position to the group is substituted by the NHR group, and in the o-positions in respect of theNHR group is substituted with a substituent by which the NHR group is sterically hindered and A includes such an aromatic group which is still further substituted.

Sterical hindrance lowers the reduction power of the aromatic phenylenediamine derivative to such an extent that it practically does no longer possess developing power for exposed silver halide. As sterically hindering substituents are particularly mentioned a halogen atom, e.g., a chlorine atom or a bromine atom, an alkyl group, e.g. a methyl group, an alkoxy group, e.g., a methoxy group or an ethoxy group, an acyl group, an acyl-substituted amino group, a sulphamyl group, a sulphonylalkyl group, a sulphonylaryl group, a sulpho group, or a carboxyl group.

As R -substituents, which can split off by the said oxidative copulation, are particularly mentioned a sulphonylalkyl, group, a sulphonylaryl group, wherein the alkyl and aryl radical may be further substituted, a sulpho group, a carbamyl group, a halogen atom, a sulphomethyl ene group, a carboxymethylene group and a phosphonic acid-substituted methyl group.

The aromatic group represented by A may be further substituted, e.g., with a halogen atom, a cyano group, a sulphamyl group, a carboxyl group, a sulpho group, an alkyl group, an aryl group, an aralkyl group or a cycloaliphatic group, or make part of a ring system comprising condensed rings selected from the group of aromatic, alicyclic, or heterocyclic rings, which may be further substituted.

Compounds preferably used in the masking process according to the present invention are represented by the following general formula:

wherein:

R' represents a hydrogen atom or an organic radical, e.g., an alkyl group, an aralkyl group, or an aryl group, including these groups in substituted form,

R represents an organic radical, eg an alkyl group, an aralkyl group, or an aryl group including these groups in substituted form, or R together with R' forms a nitrogen-containing nucleus, e.g., a piperidino, morpholino, piperazine or pyrazole ring, including such nuclei in substituted form,

each of R' and R represents a sterically hindering substituent for the NH group, e.g., a halogen atom such as a chlorine atom, an alkyl-, alkoxy-, cyano-, acyl, acyl-substituted amino-, sulphamyl-, sulphonylalkyl-, sulphonylaryl-, sulpho-, or carboxyl groups,

each of R and R represents a hydrogen atom, or a substituent e.g., a halogen atom, a cyano radical, a sulfamyl radical, a carbamyl radical, an acyl radical, a sulpho radical, a carboxyl radical, an alkoxyl group, an alkyl group, an alicyclic group, an aralkyl group or an aryl group including these groups in substituted form,

R together with R and/or R together with R forms an aromatic, a partly hydrogenated aromatic or heterocyclic condensed nucleus, including such nucleus in substituted form, or

R together with R' form a condensed nitrogen-containr ing heterocyclic nucleus including such nucleus in substituted form, or

R together with R form a condensed nitrogen containing hereto-cyclic nucleus including such nucleus in substituted form.

Preferably said compounds contain a substituent making them fast to diffusion in photographic colloids so that they can be selectively incorporated into one silver halide emulsion layer of a photographic multilayer colour material.

In order to understand a particular advantage of the method of the present invention compared with the use in masking of a coloured colour coupler the attention is drawn to the fact that when according to the masking system described in US. patent specification 2,860,974 a green coloured colour coupler is incorporated in the green-sensitive silver halide emulsion layer, this colour coupler exerts a filtering action upon the underlaying redsensitive silver halide emulsion layer in that it absorbs red light, which results in a decrease in sensitivity for red light of the photographic colour material.

The following illustrates the preparation of oxidatively coupling compounds preferably used in a masking process according to the present invention,

PREPARATION l 2, 6 -dimethyl-4-N-n-h exadecyl-N- B-N- meth ylsulphonyl) -amino] ethylaniline CH3 CIIrSOzNIICHeCH: i

N Nll2 CII3-(CH2)J5 i 12.1 g. (0.01 mole) of 3,5-dimethylaniline, prepared according to A. Van Loon, Rec.Tr.Ch.Pays-Bas 79 (1960) 986, and 7 cc. of 98% formic acid are refluxed for minutes. The water formed is distilled under reduced pressure on an oil bath of 100 C. The residue is recrystallized from petroleum naphtha. Yield: 10.8 g. of 3,5-dimethylformanilide. Melting point: 74 C.

10.8 g. (0.072 mole) of this formanilide and 22.2 g. (0.072 mole) of n-hexadecyl bromide are dissolved in 100 cc. of ethanol. To this solution is added a solution of 4.1 g. (0.072 mole) of potassium hydroxide in 100 cc. of ethanol. This mixture is refluxed for 12 hours. The potassium bromide formed is filtered by suction and the filtrate is evaporated to dryness under reduced pressure. The dry residue is heated for 1 hour in 50 cc. of strong hydrochloric acid in order to hydrolyze the formylamino linkage.

On cooling the hydrochloride precipitates, which is recrystallized from acetonitrile. Yield: 10 g. of 3,6- dimethyl-N-n-hexadecylaniline hydrochloride. Melting point: C.

3.31 g. (0.01 mole) of this aniline together with 2.34 g. (0.01 mole) of B-methylsulphonylamino ethylbromide are dissolved in 100 cc. of ethanol and refluxed for 15 hours with 1.7 g. (0.03 mole) of sodium carbonate. After evaporation to dryness, the residue is washed with water and methanol, and then recrystallized from n-hexane. Yield: 2.3 g. of 3,S-dimethyl-N-n-hexadecyl-N-(,B-methylsulphonylamino)-ethylaniline. Melting point: 67 C.

To a solution of 5 mmole of 2,5-dich1orophenyldiazonium chloride cooled below 5 C., is added a solution of 2.2 g. (4.75 mmole) of the foregoing compound in 20 cc. of acetic acid. To this mixture sodium acetate is added for adjusting the pH to about 5, whereupon the mixture is stirred for further /2 hour. After pouring this mixture onto ice, the precipitate formed is filtered by suction, washed with water, dried, and twice recrystallized from petroleum naphtha. Yield: 2 g. of 4-[N-n-hexadecyl- N-(fi-methyl sulphonylamino)-ethyl]-amino-phcnyl azo- 2,5-dichlorobenzene. Melting point: about 100 C.

10 g. of this azo compound are reduced in cc. Of acetic acid under hydrogen pressure with Raney nickel as a catalyst. After filtration, the filtrate is poured onto ice and alkalized by means of ammonium hydroxide. The precipitate formed is filtered by suction, washed with water and recrystallized from acetonitrile. Yield: 5.5 g.

of 2,6 dimethyl-4-N-n-hexadecyl-N-(,8-methylsulphonylamino)-ethylaniline. Melting point: 70 C.

PREPARATION 2 2,6-dimethyl-3 -chloro-4-4-n-hexadecylaminoaniline hydrochloride l CH 24.9 g. (0.15 mile) of 2,4-dimethyl-6-nitroaniline, prepared according to A. Van Loon, Rec.Tr.Chim. Pays-Bas 79 (1960) 986, are dissolved in 120 cc. of strong hydrochloric acid and diazotized at C., after having added a solution of 12 g. of sodium nitrite in 120 cc. of water. This solution is poured at 25 C. in a solution of copper (I) chloride, (freshly prepared from 52 g of hydrated copper sulphate) in 250 cc. of strong hydrochloric acid. The formed precipitate is collected and recrystallized from n-hexane. Yield: 17 g. of 2-chloro-3,5-dimethylnitrobenzene. Melting point: 50 C.

12.5 g. of this nitro compound are reduced in 150 cc. of ethanol under hydrogen pressure with Raney nickel as a catalyst. After filtration, the filtrate is evaporated to dryness. The residue is mixed with 45 cc. of 98% formic acid and heated for 1 hour on an oil bath of 120 C. After evaporation under reduced pressure and recrystallization from petroleum naphtha, 12 g. of 2-chloro-3,5- dimethyl-formanilide are obtained. Melting point: 119 C.

To a solution of 15.7 g. (0.085 mole) of this formanilide and of 26 g. (0.085 mole) of n-hexadecyl bromide in 100 cc. of anhydrous ethanol, a solution is added of 4.8 g. of potassium hydroxide in 150 cc. of anhydrous ethanol. This mixture is refluxed for hours. After evaporating to dryness and heating the mixture for 1 hour in 100 cc. of strong hydrochloric acid, the formylamino linkage is hydrolyzed. This solution is allowed to cool, and the crystals formed are filtered by suction and recrystallized from acetonitrile. Yield: 16.5 g. of 2- chloro-3,S-dimethyl-N-n-hexadecylaniline hydrochloride. The corresponding base is set free therefrom by means of ammonium hydroxide, whereupon it is recrystallized from methanol. Yield: 10.3 g. Melting point: 53 C.

To a solution of 2,5-dichlorophenyl-diazonium chloride (0.021 mole) cooled till 5 C. is added a solution of 8.7 g. (0.021 mole) of the foregoing hydrochloride in 100 cc.

of acetic acid. The pH of the mixture is adjusted to 5 by means of sodium acetate. After allowing to stand for 12 hours at 20 C., the reaction mixture is poured into Water. The precipitate formed is recrystallized successively from isopropanol and petroleum naphtha. Yield: 5.4 g. of 2,6-dimethyl-3 chloro-4-n-hexadecylaminophenylazo-2,5-dichlorobenzene. Melting point: 79 C.

5 g. of this azo compound are reduced under hydrogen pressure in 150 cc. of acetic acid by means of Raney nickel as a catalyst. After filtration of the reaction mixture, the filtrate is poured into a mixture of 150 cc. of strong hydrochloric acid and 20 cc. of water. The precipitate formed is collected and recrystallized from ethanol. Yield: 3 g. of 2,6-dimethyl-3-chloro-4-n-hexadecylaminoaniline hydrochloride. Melting point: about 124 C.

PREPARATION 3 2, 3,5 ,6-tetramethyl-4-n-decylamino-aniline dihydrochloride Ila C 0 IT:

A mixture of 3.88 g. (0.02 mole) of nitroaminodurene (prepared according to C. Ingham, J. Chem. Soc. (1939) 984, or according to G. Illuminati, J. Am. Chem. Soc. 74 (1952) 4952) and of 30 cc. of 98% formic acid is refluxed for 1 hour. The excess formic acid is distilled under reduced pressure. The residue is recrystallized successively from ethanol and xylene. Yield: 3 g. of nitroformylaminodurene. Melting point: 227 C.

3 g. of this nitro compound are reduced under hydrogen pressure in 100 cc. of ethanol by means of Raney nickel as a catalyst. After filtration and cooling, 1. 6 g. of aminoformylaminodurene crystallizes. Melting point: 264 C. (with decomposition).

A mixture of 1.92 g. (0.01 mole) of the foregoing compound, 2.42 g. (0.011 mole) of n-decyl bromide, 1.06 g. (0.01 mole) of sodium carbonate, and 50 cc. of ethylene glycol monomethyl ether is refluxed for 48 hours. After filtration and concentration of the filtrate, 1.9 g. of crystlline reaction product is obtained, which is recrystallized from acetonitrile. Yield: 1.05 g. of n-decyl aminoformylaminodurene. Melting point: 135 C.

2.5 g. (0.075 mole) of this compound is hydrolyzed by boiling it for 1 hour in cc. of strong hydrochloride acid. The reaction mixture is cooled and filtered by suction. The crystals obtained are recrystallized from ethanol hydrochloric acid. Yield: 2.2 g. of 2,3,5,6-tetramethyl-4- n-decylaminoaniline dihydrochloride.

PREPARATION 4 2-bromo-4-n-hexadecylamino-6-methoxyaniline hydrochloride 34 g. (0.2 mole) of 2-methoxy-4-nitroaniline, dissolved in 350 cc. of acetic acid, are brominated below C. by dropwise adding 11 cc. (0.2 mole) of bromine. The reaction mixture is poured onto ice, whereupon the precipitate obtained is filtered by suction and recrystallized from xylene. Yield: 32.2 g. of 2-methoxy-4-nitro- 6-bromoaniline. Melting point: 140 C.

14.82 g. of this aniline dissolved in a mixture of 200 cc. of acetate acid, cc. of 5 N hydrochloric acid and 10 cc. of strong sulphuric acid are diazotized at 5 C. by means of a solution of 4.2 g. sodium nitrite in 20 cc. of water. Below 5 C., 66 g. of 40% hypohosphorous acid are added. The temperature of the reaction mixture is allowed to rise slowly to 20 C., whereupon this temperature is maintained for 12 hours. The precipitate formed is filtered by suction and added to a certain amount of 1 N hydrochloric acid in order to form a suspension. From this suspension the precipitate is steamdistilled. Yield: 11 g. of 3-bromo-5methoxy-nitrobenzene. Melting point: C.

35 g. (0.15 mole) of this nitro compound are heated for 12 hours at 120 C. in a mixture of 200 cc. of acetic acid, cc. of strong hydrochloric acid and 140 g. of crystalline tin(II) chloride. This reaction mixture is alkalized by means of ammonium hydroxide and steamdistilled. Yield: 24.7 g. of 3-bromo-5-methoxyaniline. Melting point: 51 C.

All of this aniline is heated for 1 hour at C. in 50 cc. of 98% formic acid. After evaporating to dryness of the reaction mixture under reduced pressure, the residue is washed with water, dried, and recrystallized from xylene. Yield: 25.6 g. of 3-bromo-S-methoxy-formanilide. Melting point: C.

To 5.4 g. (23.5 mmole) of this formanilide and 7.3 g. (23.55 mmole) of n-hexadecyl bromide in 80 cc. of ethanol, is added a solution of 1.5 g. of potassium hydroxide (25.8 mmole) in 100 cc. of ethanol. This reaction mixture is refluxed for 2 hours. After evaporating the ethanol under reduced pressure and after adding 80 cc. of strong hydrochloric acid, the formylamino linkage is hydrolyzed by heating the reaction mixture for A2 hour at 120 C. After cooling, the precipitate formed is filtered by suction, washed with N hydrochloric acid, and recrystallized from acetonitrile containing a little hydrogen chloride. Yield: 3.4 g. of 3-bromo-5-methoxy-N-n-hexadecylaniline hydrochloride. Melting point: 74 C. Melting point of the free base: 48 C.

To a solution of 3.4 g. (7.35 mmole) of the foregoing compound in 40 cc. of acetic acid, a solution of 7.4 mmole of 2,5-dichlorophenyldiazonium chloride is added below 5 C. Sodium acetate is added until a pH of 5 is reached. Then the reaction mixture is stirred for 3 hours without cooling so that the temperature rises slowly to 20 C. After pouring the mixture into water, the precipitate formed is Washed with water and twice recrystallized from ethylene glycol monomethyl ether. Yield: 3.1 g. of 2 bromo-4-n-hexadecylamino-6-methoxyphenyLazo-Z,5- dichlorobenzene. Melting point: 91 C.

All of this azo compound is dissolved in 35 cc. of warm acetic acid. To this solution is added a solution of 3.5 g. of crystalline tin(II) chloride in cc. of acetic acid and cc. of ethanolic hydrochloric acid. After having poured the reaction mixture onto ice, the precipitate formed is filtered by suction and recrystallized successively from acetonitrile and from acetic acid containing a little ethanolic hydrochloric acid. Yield: 1.2 g. of 2 bromo 4-n-hexadecylamino-6-methoxyaniline hydrochroride. Melting point: about 100 C.

PREPARATION 5 2 chloro-6-methyl-4-(N-n-hexadecyl-N-y-sulphopropyl)- aminoaniline hydrochloride 207 g. (1.11 mole) of 2-methyl-4-chloro-6-nitroaniline (prepared according to A Claus, Ann. 274 (1893) 297) dissolved in a mixture of 5 litres of acetate acid, 1 litre of 5 N hydrochloric acid, and 200 cc. of strong sulphuric acid, are diazotized at 5 C. by means of a solution of 78 g. of sodium nitrite in 250 cc. of water. At 2 C., 1220 g. of 40% hypophosphorous acid are added. This mixture is allowed to stand for 12 hours at C., Whereupon it is poured onto 7 kg. of ice. The precipitate formed is filtered by suction, washed with water, and

steam-distilled from its solution in 1 N hydrochloric acid. Yield: 94.5 g. of 3-chloro-S-methyl-nitrobenzene. Melting point: 56 C.

All of this nitro compound, i.e. 0.552 mole, is heated for 12 hours at 120 C. in a mixture of 600 cc. of acetic acid, 400 cc. of strong hydrochloric acid, and 510 g. (2.22 mole) of hydrated tin(II)chloride. After alkalizing this reaction mixture by ammonium hydroxide, 70 g. of 3-chloro-5-methylaniline are collected by steam distillation. This product is heated for 1 hour in 700 cc. of formic acid. After evaporating this reaction mixture to dryness, the residue obtained is recrystallized from petroleum naphtha. Yield: 70 g. of 3-chloro-5- methylformanilide. Melting point 94 C.

To a solution of 8.48 g. (0.05 mole) of this compound and 15.75 g. of n-hexadecyl bromide in 100 cc. of anhydrous ethanol is added a solution of 3.25 g. of potassium hydroxide in 100 cc. of ethanol. This mixture is refluxed for 2 hours and subsequently evaporated to dryness under reduced pressure. The formylamino linkage is hydrolyzed by boiling the residue obtained for 1 hour in 100 cc. of strong hydrochloric acid. The crystals formed by cooling are filtered by suction and recrystallized from ethanolic hydrochloric acid. The hydrochloride obtained is transformed into its base by dissolving it in ethanol and by adding ammonium hydroxide. The precipitate obtained is recrystallized from methanol. Yield: 8.6 g. of 3-chloro-5-methyl-N-n-hexadecylaniline. Melting point: 28 C.

7.31 g. of the foregoing base is heated for 12 hours at 140 C. together With 3 g. of propane sultone. The obtained viscous mass is dissolved in 30 cc. of acetic acid and added to an aqueous solution of 2,5-dichlorophenyl-diazonium chloride. Thereupon sodium acetate is added until a pH of 4. After stirring for another 3 hours at 20 C., the reaction mixture is poured onto ice, whereafter g. of potassium hydroxide are added. The precipitate formed is filtered by suction, Washed with water, and recrystallized successively from dimethylformamide and n-butyl acetate. Yield: 4 g. of 2-chloro- 6-methyl 4 (N-n-hexadecyl-N-v-sulphobutyl)-aminoazo-2-5'-dichlorobenzene. All of this azo compound is dissolved at C. in 30 cc. of acetic acid and reduced at 75 C. by adding thereto a solution of 5 g. of hydrated tin(II) chloride in 25 cc. of ethanolic hydrochloric acid.

The mixture is evaporated to dryness and water is added to the residue. The precipitate formed is dissolved in n-butyl acetate. The precipitate settles again immediately whereupon it is recrystallized from a mixture of 15 cc. of 5 N hydrochloric acid and 15 cc. of ethanol, and simultaneously transformed into its hydrochloride. Yield: 2.2 g. of 2-chloro-6-methyl-4-(N-nhexa decyl N 'y sulphopropyl)-aminoaniline hydrochloride. Melting point: about C.

PREPARATION 6 2-bromo-6-methyl-4 (N-n-hexadecyl-N--, -sulphopropyl aminoaniline-hydrochloride 225 g. (1.21 mole) of 3-bromo-5-methylaniline, prepared according to C. Gibson, J. Chem. Soc. (1929) 1229, are refluxed for 1 hour in 380 cc. of formic acid. After having added water, the precipitate formed is filtered by suction Washed with water, dried, and recrystallized from xylene. Yield: 215 g. of 3-bromo-5-methylformanilide. Melting point: 98 C.

214 g. (1 mole) of the foregoing formanilide together with 305 g. (1 mole) of n-hexadecyl bromide are dissolved in 3 litres of anhydrous ethanol. To this solution is added a solution of 57 g. of potassium hydroxide in 3.8 litres of anhydrous ethanol. The mixture is refluxed for 2 hours. Then, the ethanol is evaporated and the formylamino linkage is hydrolyzed by adding 3 litres of strong hydrochloric acid, and heating the mixture for 30 minutes on an oil bath at C. After cooling, the precipitate formed is filtered by suction, Washed with 5 N hydrochloric acid, and recrystallized from ethanol containing a little hydrogen chloride. Yield: 315 g. of 3-bromo 5 methyl-N-n-hexadecylaniline hydrochloride. Melting point: 100 C. (with decomposition).

16.4 g. (0.04 mole) of the base corresponding with this hydrochloride together with 6 g. (0.048 mole) of propane-sultone are heated for 12 hours at C. The obtained viscous mass is dissolved in 60 cc. of acetic acid and added below 5 C. to an aqueous solution of 2,S-dichlorophenyldiazonium chloride. By means of sodium acetate the pH of the solution is adjusted to about 4. After having stirred the solution for 30 minutes at 20 C., it is poured onto ice and mixed with g. of potassium hydroxide. The precipitate formed is filtered by suction, washed with water and recrystallized twice from acetic acid. Yield: 11 g. of 2-bromo- 6-methyl 4 (N-n-hcxadecyl-N-y-sulphobutyl)-aminoazo-2,5'-dichlorobcnzene. Melting point: about 200 C.

10.5 g. (0.015 mole) of the foregoing azo compound are dissolved in 60 cc. of acetic acid at 80 C., and at this same temperature reduced by adding a solution of 12 g. of crystalline tin(II) chloride in 30 cc. of ethanolic hydrochloric acid. After having stirred for minutes, the solution is poured onto ice. The precipitate formed is filtered by suction, washed with water, and recrystallized successively from acetonitrile and from a mixture of equal parts of ethanol and 5 N hydrochloric acid. Yield: 4.5 g. of 2-bromo-6-methyl-4-(N-n-hexadecyl- N-y-sulphopropyl)-aminoaniline hydrochloride. Melting point: about 120 C.

PREPARATION 7 2,6-dibromo-4- (N-n-hexadecyLN-y-sulphopropyl)- aminoaniline hydrochloride g. (0.08 mole) of 3,5-dibromoaniline are heated for 1 hour at 120 C. in 75 cc. of 98% formic acid. This solution is evaporated to dryness, whereupon the residue obtained is recrystallized from acetonitrile. Yield: 19 g. of 3,5-dibromoformanilide. Melting point: 158 C.

All this formanilide (0.068 mole) and 20.74 g. (0.068 mole) of n-hexadecyl bromide are dissolved in 170 cc. of ethanol. To this solution a solution of 4 g. of potassium hydroxide in 170 cc. of ethanol is added, whereupon the whole is refluxed for 3 hours. The potassium bromide formed is filtered by suction, the filtrate is evaporated to dryness, and the residue is hydrolyzed by boiling it for 1 hour in 150 cc. of strong hydrochloric acid. Then, the solution is allowed to cool and the hydrochloride crystals formed are filtered by suction. From these crystals the base is set free by dissolving them in cc. of ethanol, and ad ding thereto 20 cc. of ammonium hydroxide. After having added 100 cc. of ice water, the precipitate formed is filtered by suction, and recrystallized from methanol. Yield: 9 g. of 3,5-dibromo-N-n-hexadecylaniline. Melting point: 53 C.

4.75 g. (0.01 mole) of this aniline and 4 g. (0.02 mole) of propane-sultone are heated for 12 hours at 140 C. The viscous liquid thus obtained is dissolved in cc. of acetic acid and added to a cooled solution of 2,5-dichlorophenyl diazonium chloride. After having adjusted the pH of the mixture to 4 by means of sodium acetate, a solution of g. of potassium hydroxide in 100 cc. of water is added gradually in 2 hours and below 10 C. This mixture is poured into water, whereupon the precipitate formed is filtered by suction, washed with a solution of sodium chloride, and recrystallized from n-butanol. Yield: 3 g. of 2,6-dibromo-4-(N-n-hexadecyl-N-'y-sulphopropyl)-aminophenyl-azo-25,5-dichlorobenzene. Unsharp melting point: 205 C.

25 g. of this azo compound are dissolved in 150 cc. of acetic acid. To this solution is added dropwise at 30 C. a solution of 40 g. crystalline tin(II) chloride in 150 cc. of ethanolic hydrochloric acid. After having poured this mixture into about 6 parts by volume of ice, the precipitate formed is filtered by suction and recrystallized from a mixture of ethanol and ammonium hydroxide. The obtained base is transformed into its hydrochloride by recrystallization from a mixture of ethanol and 5 N hydrochloric acid. Yield: 10.5 g. of 2,6-dibromo-4-(N-n-hexadecyl-N-v-sulphopropyl)- aminoaniline hydrochloride. Melting point: 110 C. (with decomposition).

By oxidative coupling with a magenta-forming .colour coupler of the pyrazolone type the p-phenylenediamine derivatives yield a cyan mask dyestuff compensating for the unwanted side-absorption in the red region of the spectrum of the magenta dyestulf formed by colour development.

So, the p-phenylenediamine derivatives described in the present invention when used in photographic colour materials are preferably incorporated into a light-sensitive silver halide emulsion layer containing a magenta-forming colour coupler of the pyrazolone type.

Of course, the p-phenylenediamine derivatives forming a green mask may be used in combination with compounds forming a yellow mask, which compensates for the unwanted side-absorption in the blue of the primary magenta dyestufi formed on colour development.

The use of such yellow mask-forming compounds in combination with colour couplers of the pyrazolone type is described e.g. in the UK. patent specification 975,932. In this way a well-balanced complete compensation for the side-absorptions in the red as well as in the blue of the magenta dye image can be obtained.

Colour couplers of the pyrazolone type which are particularly suitable for being used in a masking process according to the present invention are 3-acylaminopyrazolone compounds e.g. thos described in the Belgian patent specification 654,110 and UK. patent specification 1,007,847, the latter specification containing a detailed description of the preparation of such couplers.

According to a preferred embodiment of the present invention the mask-forming compound is incorporated into the light-sensitive silver halide emulsion layer containing the magenta-forming colour coupler in a form made fast to diifusion by the introduction in the structure of said compound of an aliphatic radical containing from 5 to 20 carbon atoms in straight line.

The silver halide emulsion is prepared by means of the usual photographic colloids such as e.g. gelatin, polyvinyl alcohol, casein, zein, collodion or other natural or synthetic colloids. The silver halide emulsion can be coated on a support consisting of paper, glass, nitrocellulose, cellulose esters, such as cellulose triacetate, polyester, polystyrene or other natural or synthetic resins, and may form part of a photographic material with one or more silver halide emulsion layers.

A multilayer photographic colour material usually comprises the following elements: a support, a red-sensitive emulsion layer having a cyan-forming colour coupler, a green-sensitive emulsion layer having a magenta-forming colour coupler and a blue-sensitive emulsion layer having a yellow-forming colour coupler. There is a yellow filter composed in most of the cases of a gelatin layer containing dispersed colloidal silver, located between the blue-sensitive emulsion layer and the green-sensitive emulsion layer. When used in a form fast to diffusion it is not only possible to incorporate the colour couplers into the light-sensitive silver halide emulsion layer itself, but also to incorporate them into an adjacent non-light-sensitive colloid layer or into a non-light-sensitive layer, which is separated from the light-sensitive emulsion layer by a water-permeable colloid layer.

Summarizingly, a photographic colour negative masked according to the present invention can be formed as follows: after exposure to a coloured original of a photographic material containing in a silver halide emulsion layer sensitive to green light a magenta-forming colour coupler of the pyrazolone type and a mask-forming compound according to the present invention, silver halide is reduced to silver at the exposed areas in a colourdeveloping bath containing an aromatic primary amino colour developing agent, which at the same time is oxidized. The oxidized developing agent reacts with the colour coupler and forms a dyestuff, the mask-forming compound according to the invention not being aifected. After the colour development the photographic material is treated with an alkaline oxidizing bath, such as a photographic bleaching bath wherein the oxidative coupling of the mask-forming compound with the residual pyrazolone takes place. Thereupon the colour material is washed with water, fixed and dried.

The following aromatic amino compounds can be used as colour developers for such materials: N,N-dialkyl-pphenylenediamines, such as N-N-diethyl-p-phenylenediamine and N,N-diethyl-Z-methyl-p-phenylenediamine, and derivatives thereof, such as N,N-dialkyl-N -sulphomethylor N,N-dialkyl-N -carboxymethyl-p-phenylenediamine.

The following examples illustrate the invention.

EXAMPLE 1 225 g. of a photographic silver bromide iodide emulsion, prepared by means of 50 g. of silver nitrate and 80 gof gelatin pro kg., are melted at 40 C. with 150 cc. of water. To this emulsion are added successively:

8 cc. of 1 N acetic acid Solution of 3.6 g. of 1-(4-n-hexadecylsulphonyl-phenyl)- 3-(4'-sulphobenzoylamino)pyrazolone-S in 3.6 cc. of 2 N sodium hydroxide, and 32.5 cc. of water 2.5 g. of the compound of preparation 7, dissolved in cc. of 2 N sodium hydroxide, 5 cc. of ethanol, and cc. of water.

After having incorporated a hardening agent, a stabilizing agent, and a dispersing agent, the required amount of water is added for coating with this emulsion 10 sq.m. of film base. The material thus obtained is exposed behind a grey step wedge of constant 0.15, and developed for 9 minutes at C. in a colour developing bath of the following composition:

G. Sodium hexametaphosphate 2 N,N-diethyl-p-phenylenediamine hydrochloride 3 Sodium sulphite 4 Sodium carbonate 57 Hydroxylamine hydrochloride 1.5 Potassium bromide 1 Water to make 1000 cc. (pH:10.6).

After having washed this material for 5 minutes, it is fixed for 5 minutes at 20 C. in a fixing bath of the following composition:

G. Sodium thiosulphate 200 Sodium bisulphite Potassium alum 20 Equimolecular mixture of sodium acetate and acetic acid 20 Boric acid 7.5

Water to make 1000 cc. (pH=4).

Then, the material is washed and bleached for 5 minutes at 20 C. in a bleaching bath of the following composition:

G. Potassium hexacyanoferrate(III) 100 Potassium bromide 15 Borax 20 Magnesium sulphate 50 Water to make 1000 cc. (pl-1 8.6).

The material is washed for 5 minutes and fixed again for 5 minutes at 20 C. in a fixing bath of the following composition:

G. Sodium thiosulphate 130 Borax 20 Magnesium sulphate 50 Water to make 1000 cc. (pl-1:89).

Finally, the material is rinsed for 10 minutes and dried.

This way, an image is obtained consisting of a magenta wedge and a cyan wedge (absorption maximum: 650 nm.). This cyan wedge possesses a gradation opposite to that of the magenta wedge, and thus on making a print, compensates the disturbing side-absorptions of the magenta dye in the red region of the spectrum.

Cir

12 EXAMPLE 2 225 g. of a photographic silver bromide iodide emulsion, prepared by means of g. of silver nitrate and g. of gelatin pro kg., are melted at 40 C. with cc. of water. To this emulsion are added successively:

12 cc. of I N acetic acid 3.6 g. of 1-(4'-n-hexadecyclsulphonylphenyl)-3-4'-sulphobenzoylamino)-pyrazolone-5, dissolved in 3.6 cc. of 2 N sodium hydroxide and 32.5 cc. of water 2.5 g. of 1-methyl-4-n-pentadecylquinolone-2-(4'-carboxymethoxyphenyl)-sulphonylhydrazone, dissolved in 5 cc. of 2 N sodium hydroxide, 12.5 cc. of diacctone alcohol, and 32.5 cc. of water.

2.5 g of the compound of preparation 7, dissolved in 5 cc. of 2 N sodium hydroxide, 5 cc. of ethanol, and 15 cc. of water.

After having incorporated a hardening agent, a stabilizing agent and a dispersing agent, the required amount of water is added for coating with this emulsion 10 sq.m. of film base. The material thus obtained is exposed behind a grey step wedge of constant 0.15, and further processed as described in Example 1. This way, an image is obtained consisting of a magenta wedge and a green wedge absorbing in the red and blue region. This green wedge possesses a gradation opposite to that of the magenta wedge, and thus on making a print compensates the disturbing sideabsorptions of the magenta dye in the blue and red regions of the spectrum.

What we claim is:

1. In a method of forming a color-corrected image in a photgoraphic element having at least one silver halide emulsion layer containing a color coupler of the pyrazolone type which on development by reaction with the oxidation product of an aromatic amino developing agent forms a primary dye image which absorbs a major proportion of light in one region of the visible spectrum, and undesirably absorbs a minor proportion of light in another region of the visible spectrum, which method comprises treating said photographic element, after image-wise exposure and color development, with an oxidizing bleaching solution in the presence of a mask-forming compound to cause oxidative coupling of residual coupler and maskforming compound, said mask-forming compound corresponding to the formula:

N NIIRa R: I

R5 R4 whereln:

R is hydrogen, an alkyl group, an aralkyl group or an aryl R is an alkyl group, an aralkyl group, or an aryl group, or R together with R forms a nitrogen-containing heterocyclic nucleus,

R is hydrogen or a substituent splitting off by said coueach of R and R is a sterically hindering substituent for the NHR group,

each of R and R is hydrogen, or an aliphatic, alicyclic,

aralkyl or aryl substituent, or

R together with R and/or R together with R forms an aromatic, partly hydrogenated aromatic or heterocyclic condensed nucleus,

R toegther with R forms a condensed nitrogen-containing heterocyclic nucleus, and

R together with R forms a condensed nitrogen-containing heterocyclic nucleus,

wherein each of said sterically hindering substituents in the said mask-forming compound is a halogen atom, an alkyl group, an alkoxy group, an acyl group, an acyl-substituted amino group, sulfonyl, a sulfonyl-alkyl group, a sulfonylaryl group, sulpho, or carboxy in acid or salt form, and

13 said substituent which splits off by said oxidative coupling is a sulfonylalkyl group, a sulfonylaryl group, sulpho, carbamyl, a halogen atom, sulfomethylene, carboxymeth ylene or phosphoric acid-substituted methyl.

2. The process of claim 1 wherein said primary dye image is magenta colored and said mask image is green to cyan colored.

3. The process of claim 1 wherein said mask-forming compound is present in said emulsion layer and includes an aliphatic substituent containing from about 5-20 carbon atoms in a straight chain.

4. The method of claim 1, wherein the oxidative coupling is carried out by means of a photographic bleaching bath containing potassium hexacycyanoferrateflll).

5. A color photographic element having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a color coupler for magenta of the pyrazolone type and in non-migratory state a mask-forming compound corresponding to the following general formula:

R5 R3 R i N [NH2]NHR3 R2 RI R4 wherein:

R' is hydrogen, an alkyl group, or an aryl group,

R' is an alkyl group or an aryl group, or

R' together with R forms a nitrogen-containing heterocyclic nucleus,

R is hydogen or a substituent splitting off by said coueach of R' and R is a sterically hindering substituent se ected from a halogen atom, an alkyl group, an alkoxy group, and

each of R and R is hydrogen, an alkyl group, an alkoxy group or a halogen atom.

References Cited UNITED STATES PATENTS 3,028,237 4/ 1962 Lolfer 96-9 FOREIGN PATENTS 519,872 5/ 1953 Belgium.

J. TRAVIS BROWN Primary Examiner US. Cl. X.R. 9656.5, 74 

